(a) Field of the Invention
This invention relates to fiber optics and more particularly to a method of etching a diffraction grating on an optical fiber for uses including in fiber optic grating couplers.
(b) Brief Description of the Prior Art
Since about 1980, the use of fiber optics for telecommunications has been rapidly expanding. It is desirable to impart a diffraction grating pattern on the surface of an optical fiber. The diffraction grating is used as a means of introducing a signal into the optical fiber for transmission and for coupling of fiber optics.
The methods available of producing a diffraction grating on the surface of an optical fiber are essentially limited to producing a grating on a flattened portion of the fiber and the grating thus produced covers only about 50 percent of the surface of the optical fiber in the section whose grating is imposed on the fiber.
I have invented a new method of forming a diffraction grating on the entire cylindrical surface of the thin wall cladding in the region of the grating covers. By imposing the grating on the entire surface of the optical fiber, the coupling efficiency of a signal into the optical fiber is vastly increased. My method provides a low cost method of producing the diffraction grating with high reliability and uniformity of grating pattern.
Another use of the improved optical fiber grating is to separate closely spaced optical wave lengths providing a means to use light of different wavelengths to transmit different data.